The present invention relates to universal joints, and more particularly, to an apparatus and method for servicing staked universal joints.
Universal joints are widely used in motor vehicle drivetrains for interconnecting a pair of rotating shafts to permit movement and flex within the drivetrain. Universal joints commonly include a pair of bifurcated yokes secured to the shafts and interconnected with a cruciform. The cruciform includes four orthogonal trunnions arranged in opposed pairs with each pair mounted in a pair of aligned apertures formed in one of the bifurcated yokes. A bearing assembly is secured in each aperture and around each trunnion to minimize friction as the yokes pivot.
Snap rings and staking are the two most common retention methods used to couple bearing cups to the yokes and simultaneously center and align the axes of the shafts. For proper balanced operation of the driveshaft, the rotary axis of the rotating shafts and yokes must be aligned. The rotary axes are typically aligned by centering the cruciform between the yokes and properly positioning the bearing cups in the apertures. Staking and similar permanent yoke deformation operations use expensive machinery to center the bearing cups, crossmembers, and yokes, and then deform the yokes to secure the bearing cups in a balanced position. While staking provides a well balanced drive shaft, special tools are required for aligning the axes and deforming the yokes when servicing a staked U-joint. Therefore, the number of repair shops capable of servicing the staked U-joints is limited. Further, it is difficult to securely stake a bearing cup in a yoke that has been previously staked due to the already deformed yokes and therefore, most staked universal joint driveshafts are not serviced but are replaced.
Snap rings are commonly used to secure the bearing cups within the yokes in place of staking and allow for ease of serviceability. Snap rings generally do not align the axes of the shafts or center the U-joint as accurately as staked U-joints, but allow for easy serviceability. Snap rings typically fit within an annular groove in the apertures in the yoke so that the centerline symmetry is fixed when the yokes are machined. To increase the longevity of universal joints as well as reduce noise, vibration, and other harshness issues, manufacturers have increasingly been using the more precisely centered staked U-joints. Therefore, a method and apparatus for servicing staked U-joints is needed.